The study proposes the use of the larval adipose tissue of D. melanogaster as a model system to examine the genetic programming of aging. Mutations which affect specific groups of cells within the larval fat body will be utilized. Of particular interest are those mutant syndromes in which the affected cells show unscheduled changes resembling events that normally occur in later life of the adipose tissue. These cells in the mutant strains and their counterparts in the normal (wild-type) strain will be followed during development. Specific nuclear and cytoplasmic changes will be subjected to ultastructural, cytochemical and biochemical analysis. In addition, tissue transplantation studies will be utilized to search for cell and surface membrane changes associated with aging of the tissue.